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From: Eric Dumazet <edumazet@google.com>
To: "David S . Miller" <davem@davemloft.net>
Cc: netdev <netdev@vger.kernel.org>, Van Jacobson <vanj@google.com>,
	Neal Cardwell <ncardwell@google.com>,
	Yuchung Cheng <ycheng@google.com>,
	Soheil Hassas Yeganeh <soheil@google.com>,
	Willem de Bruijn <willemb@google.com>,
	Eric Dumazet <edumazet@google.com>,
	Eric Dumazet <eric.dumazet@gmail.com>
Subject: [PATCH net-next 1/9] tcp: switch tcp_clock_ns() to CLOCK_TAI base
Date: Fri, 21 Sep 2018 08:51:46 -0700	[thread overview]
Message-ID: <20180921155154.49489-2-edumazet@google.com> (raw)
In-Reply-To: <20180921155154.49489-1-edumazet@google.com>

TCP pacing is either implemented in sch_fq or internally.
We have the goal of being able to offload pacing on the NICS.

TCP will soon provide per skb skb->tstamp as early departure time.

Like ETF in commit 25db26a91364 ("net/sched: Introduce the ETF Qdisc")
we chose CLOCK_T as the clock base, so that TCP and pacers can share
a common clock, to get better RTT samples (without pacing artificially
inflating these samples).

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 include/net/tcp.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 770917d0caa71896b6adac06a62b150bfdc72836..c6f0bc1dc6782a1976c06932e846b3f6d708ba9f 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -732,7 +732,7 @@ void tcp_send_window_probe(struct sock *sk);
 
 static inline u64 tcp_clock_ns(void)
 {
-	return local_clock();
+	return ktime_get_tai_ns();
 }
 
 static inline u64 tcp_clock_us(void)
-- 
2.19.0.444.g18242da7ef-goog

  reply	other threads:[~2018-09-21 21:41 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-21 15:51 [PATCH net-next 0/9] tcp: switch to Early Departure Time model Eric Dumazet
2018-09-21 15:51 ` Eric Dumazet [this message]
2018-09-21 15:51 ` [PATCH net-next 2/9] tcp: introduce tcp_skb_timestamp_us() helper Eric Dumazet
2018-09-21 15:51 ` [PATCH net-next 3/9] net_sched: sch_fq: switch to CLOCK_TAI Eric Dumazet
2018-09-21 15:51 ` [PATCH net-next 4/9] tcp: add tcp_wstamp_ns socket field Eric Dumazet
2018-09-21 15:51 ` [PATCH net-next 5/9] tcp: provide earliest departure time in skb->tstamp Eric Dumazet
2018-09-21 15:51 ` [PATCH net-next 6/9] tcp: switch internal pacing timer to CLOCK_TAI Eric Dumazet
2018-09-21 15:51 ` [PATCH net-next 7/9] tcp: switch tcp and sch_fq to new earliest departure time model Eric Dumazet
2018-09-21 15:51 ` [PATCH net-next 8/9] tcp: switch tcp_internal_pacing() to tcp_wstamp_ns Eric Dumazet
2018-09-21 15:51 ` [PATCH net-next 9/9] net_sched: sch_fq: remove dead code dealing with retransmits Eric Dumazet

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